In the meantime, heat milk in a medium saucepan with pumpkin and spices over medium-low to medium heat. Bring to a simmer, and whisk in white chocolate mixture. Remove from heat, and add vanilla. Whisk until frothy.

Strain mixture through a fine-mesh sieve (there may be some pumpkin particles or lumps of white chocolate you want to strain out) and add espresso. Serve immediately, with extra cinnamon on top if desired. Makes two 6-oz. lattes, or one 12-oz latte (amounts are approximate).